Cascading settings: all cascading setting should update children on update

duo_features_enabled cascading setting updates child objects whenever the parent is updated. This was done here: !145876 (merged)

But cascading settings that were added previously do not do this. They keep child object settings values as nil. This is cheaper on write but much more expensive on read (need to go up hierarchy to read setting value).

We should update all cascading settings to behave in the same way.